The coordinates of A and B are (0,b,c) and (a,0,c) respectively. The equation of a plane passing through O(0,0,0), is Px+Qy+Rz=0 . . . (i) It passes through A and B ∴‌‌P×0+Q×b+R×c=0 ‌ and ‌P×a+Q×0+R×c=0 ⇒‌‌‌‌‌
P
bc
=‌
Q
ac
=‌
R
−ab
Substituting the values of P,Q and R in Eq. (i), we get bcx+acy−abz=0